Damn Dirty DoS Attacks - Standard DoS Attacks

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The DoS attack variation I'm going to discuss first is the ICMP (Internet Control Message Protocol) flood, but you may recognize it as either a smurf attack, Ping flood, or Ping of Death. It is a way of sending a bunch of traffic to a victim site using “spoofed” ping messages, which ask whether a host is reachable, from forged source addresses. Each host on the IP network then replies to the ping, causing the traffic to multiply by the number of hosts responding. A host of this kind is called a smurf amplifier because it has been compromised to where it replies to the spoofed addresses.

A Nuke is an older type of DoS attack where useless ICMP data packets are sent to a victim via a modified ping utility. The result is a computer slowing down until ultimately it comes to a complete stop. This type of attack was commonly seen in online gaming and instant messaging because it was used to spam users with a constant stream of random messages. Nuking is quite uncommon nowadays because modern games and operating systems have some type of “flood control.”

A Teardrop attack is where IP fragments with overlapping payloads that are too large to communicate are sent to a target machine. The TCP/IP reassembly code usually takes care of this process when the IP packet is larger than the maximum transmission unit and the data needs to be broken up in order to be passed through different networks. However, in this case the code can't properly handle the overlapping IP fragments, ultimately crashing the corresponding operating system.

There are also unintentional attacks, which are caused by an unexpectedly large increase in popularity to the point where users are denied access to a website. This mostly happens when an extremely popular website links to a significantly less popular website. An example would be when a news story breaks that garners a lot of attention and the source website isn't used to the sudden flood of traffic that comes with popular content. Other unintentional attacks include websites being mentioned on television and servers without enough bandwidth being indexed by search engines during peak periods of activity.

So these are some examples of standard DoS attacks. Continue on to the next section to find out about distributed DoS attacks.